Some patients need nutrition, either as a supplement, or as a complete nutrition, in the smallest volume of liquid. Special care must be taken to the protein levels in such compositions.
For example, cachectic patients or persons suffering from end-stage AIDS, cancer or cancer treatment, severe pulmonary diseases like COPD (chronic obstructive pulmonary disease), tuberculosis and other infection diseases or persons that experienced severe surgery or trauma like burns can benefit from special liquid, low-volume nutrition. Furthermore, persons suffering from disorders in the throat or mouth such as oesophageal cancer or stomatitis and persons having problems with swallowing like dysphagic persons, require special liquid, low-volume nutrition. Also, persons just suffering from reduced appetite or loss of taste, will benefit from low-volume, preferably liquid, food.
Other examples of patients that require special liquid, low-volume nutrition can be elderly persons, in particular frail elderly and elderly at risk of becoming frail. In this regard, although an elderly person's energy needs may be reduced, their ability to consume products may also be diminished. For example, they may have difficulty consuming a product due to, e.g., swallowing difficulties, or due the too large amount of product they need to consume to meet the daily intake of nutrients. Hence, compliance is not optimal, and often, the intake is suboptimal, leading to suboptimal nourishment, and in the end, to malnutrition.
The aforementioned groups of patients may be extremely sensitive to food consistency and to the organoleptic properties of the product such as, for instance viscosity, mouth feel, taste, smell and colour. Also, patients such as cachectic patients, typically suffer from extreme weakness which often prevents them from sitting in a vertical position and from drinking food from a carton or even to suck it from a straw. These patients benefit well from liquid low-volume enteral compositions with a high content of nutrients, in particular proteins.
Technical difficulties exist in producing a stable, in particular a shelf-stable nutritional liquid composition having a high content of proteins. Increasing protein levels in nutritional liquid compositions for enteral use may increase the overall viscosity of the composition. This can make the liquid nutritional composition difficult to consume or administer, and can also diminish the taste of the nutritional composition. These phenomena often follow non-linear kinetics and the problems quickly increase in magnitude when the concentration of ingredients is increased above 28 weight %. Therefore, many of the commercial shelf-stable liquid products that are currently available have intact protein levels below about 9 g per 100 ml of product.
A known method to increase the protein content to a higher level without imparting viscosity is replacing part of the total protein by peptides or free amino acids. However, this seriously decreases taste appreciation and therefore voluntary intake of the nutritional composition by the patient group. Another solution is offered by replacing milk proteins by vegetable proteins which decreases the viscosity of the obtained nutritional composition. However, liquid nutritional compositions that comprise considerable amounts of vegetable proteins are often perceived as having a disagreeable taste. Furthermore, vegetable proteins are not as heat-stable as caseinate or micellar casein making it a less preferred choice of proteins.
On the other hand, many concentrates like condensed milks suffer from an incomplete nutrient profile, too high lactose levels, sticky mouth-feel, high viscosity, extreme sweetness and a high osmotic value, which is not appreciated by the consumer and increases rapidly feelings of fullness and satiety after consumption. This makes that the urge to consume more volume deteriorates rapidly once a small amount of the product has been consumed.
WO 02/098242 A1 discloses a calorically dense liquid oral supplement (2.25 kcal/ml) based on a (60:40) soy protein isolate/caseinate mixture with a protein level of 9 g/100 ml. This composition is prepared by first hydrating soy protein into water after which casein can be added to the protein slurry. This slurry is pH adjusted, subjected to a heat-treatment followed by inclusion of a fat source. As a last step, a solution of carbohydrates is added to this mixture followed by pH adjustment and thermal processing.
U.S. Pat. No. 5,683,984, and the corresponding EP patent 0 686 396 B1, teach to prepare a liquid micellar protein composition to which digestible carbohydrates and various minerals are added, followed by mixing and dissolving of these ingredients.
EP 2 363 028 A1 discloses a method of producing a liquid nutritional supplement, the method comprising: providing a mixture including water and a protein source including milk protein isolate and/or canola plant proteins; subjecting the mixture to direct steam injection (DSI); and homogenizing the mixture. Any further ingredients, such as carbohydrates, fats/emulsifiers vitamins and minerals, are added to a protein slurry mixture or added without premixing into a dry blend.
WO 2008/041219 discloses a dry milk protein composition comprising at least 12.5 wt % of a slow digesting milk protein, in particular micellar casein. The milk protein composition is first provided in the form of a powder, which is then used into in beverages, desserts, confectionary, baked or dairy products, without pasteurisation or sterilisation. A liquid high protein shake containing 11.4% Ultra Bio-M™ (about 8 weight % of protein) is exemplified.
WO 2009072886 A1 describes a method suitable for producing a liquid enteral nutritional composition with high micellar casein content comprising a step wherein a protein solution, in which all or a major part of said protein comprises micellar casein, is subjected to an evaporation step. The method described therein starts by dissolving powderous micellar casein in water. The protein ingredients are dissolved in an excess of water, typically 150 weight % or volume % of what is required for the final composition. It is expressly mentioned that without this excess of water, the protein solution is too thick to be processed any further, including homogenisation and pasteurisation.